Good point (and one that basically points out that Mr. Whittington is the one attempting to shut off debate, in this case by basically implying Milligan is a fucking loony).
That said, the author of the paper is still just wanking at best. :-) To point at one particular issue with his conclusion: the argument from "eco-minded critics" he claims sympathy with that we have more energy than we can handle without causing damage is an argument brought from ignorance at best and from willful intent to send humanity back to the Dark Ages at worst.
Basically, the issue is not that we need to necessarily reduce our energy usage, but that we need to improve our methods of handling energy production - which is something the critics he's referring to would find a ghastly prospect, having entrenched interests in making negative predictions about humanity.
And, of course, the implication in his conclusion that because there are risks, an action is not worth taking... well, I find that attitude ethically problematic as without risks, you stunt the potential of humanity.